if you want to get free new bitcoin when the fork is coming then you can save your bitcoin at the exchanges that will supporting the new bitcoin fork. but if you don't want free coins, then you can save too another wallet like bitcoin core, mycellium, jaxx and other wallet and its better if you do in offline wallet or hardware wallet like trezor. but i think you can keep your bitcoin at the exchanges because you can have free coins and you can sell it to make free money.